How do I sell a Roblox system I already built?

A system that works in your game and nowhere else is not a product. Nine times in ten the only thing between the two is a handful of values typed into the middle of a script: your gamepass id, your coin name, your spawn point. Pull those out and you have something somebody else can install.

Steps

1. Collect every hardcoded value into one module

Go through the system and move anything that is about your game into a Config module. If a buyer has to open a script to change a number, the number is in the wrong place.

-- MySystem/Config (ModuleScript)
return {
	-- Economy: the names and ids a buyer will certainly change.
	currencyName = "Coins",
	leaderstatsFolder = "leaderstats",
	gamepassId = 0,      -- 0 = the gamepass feature stays off
	-- Balance: the numbers a buyer will want to tune.
	rewardAmount = 50,
	cooldownSeconds = 24 * 60 * 60,
	-- Presentation.
	soundId = "rbxassetid://0",
	useOwnGui = true,    -- false = the buyer wires their own
}

2. Make the system read only from Config

One require at the top, and no value typed anywhere else. This is also what makes your own game easier to re-balance.

local config = require(script.Parent.Config)

local function reward(player: Player)
	local stats = player:FindFirstChild(config.leaderstatsFolder)
	local currency = stats and stats:FindFirstChild(config.currencyName)
	if not currency then
		-- Say what is wrong, with the fix in the sentence. A buyer who sees
		-- "attempt to index nil" blames the pack.
		warn(`[MySystem] no {config.currencyName} inside {config.leaderstatsFolder}. Set it in Config.`)
		return
	end
	currency.Value += config.rewardAmount
end

3. Guard the optional parts

Anything that needs an id the buyer has not set must switch itself off rather than error. A pack that throws on install gets refunded.

local MarketplaceService = game:GetService("MarketplaceService")
local config = require(script.Parent.Config)

local function hasDoubleReward(player: Player): boolean
	if config.gamepassId == 0 then
		return false -- the feature is off until the buyer sets an id
	end
	local ok, owns = pcall(function()
		return MarketplaceService:UserOwnsGamePassAsync(player.UserId, config.gamepassId)
	end)
	return ok and owns
end

4. Export one folder, and write the five lines

Right-click the folder in Studio and Save to File — one .rbxm the buyer drags in. Then write the setup, numbered, with no step that says "configure as needed".

--[[
  MySystem v1.0

  1. Drag MySystem into ServerScriptService.
  2. Open MySystem/Config.
  3. Set currencyName to your currency (default "Coins").
  4. Optional: set gamepassId for the double reward. 0 keeps it off.
  5. Play. The reward fires on join; change cooldownSeconds to test faster.

  Needs: a leaderstats folder with your currency in it.
  Does NOT include: the GUI, data saving, or a shop.
]]

What to put in the listing

FAQ

Do I have to remove my own game's assets?

Yes, every one you do not own the right to resell. Your own models and scripts are yours; a mesh or a sound you grabbed from somewhere is not, and reselling it is the one thing that gets a listing taken down. If a placeholder is needed, ship a grey box and say so.

Should I sell it as a model or as a file?

A .rbxm file. A Roblox model is public, uncontrolled and easy to re-upload; a file is delivered per buyer, and on Risor each download carries the mark of the delivery it came from, so a leaked copy traces back to it.

What licence should I give?

A non-exclusive licence to use and modify it in the buyer's own experiences, commercial ones included, and no right to resell or redistribute the source. That is the licence every Risor pack carries, and it is the one buyers expect.

How much is a system worth?

What a buyer saves by not building it. A daily-reward module is an evening's work and prices like one; a full inventory system with saving, a UI and migrations is a week, and sells like one. Pricing it below your own build time teaches buyers that the next version is cheap too.